167 



On September 30, when HILDA entered the Gulf, the conditions encountered 

 were apparently those typical of late summer, the Gulf not having been 

 disturbed by any previous hurricsmes nor by any widespread and severe northers. 

 ■Ehe surface waters over much of the Gulf were of relatively uniform temperature, 

 approximately 29 - 30 C, as indicated in Figure 2. The temperature depth 

 structure, based upon a few bathythermograms, collected prior to hurricane 

 HILDA and upon the limited available climatic data, consisted of a well mixed 

 layer from the surface to approximately 60 meters depth with a normal seasonal 

 thermocline beneath. In Figure 2, the path of the hurricane during its 

 development stage may be seen to have followed along approximately the center 

 of the initially high temperature zone . 



CRUISE PLANS 



As hurricane HILDA became a severe hurricane on October 2, efforts 

 were made to locate a research vessel which could be used to maice a survey 

 in the hurricane area immediately after the passage of the storm. The 

 Galveston Biological Laboratory in Galveston, Texas, was able to provide the 

 90-foot shrimp boat GQS III, and a decision was made on October 2 to begin 

 the cruise on October 6. The Laboratory provided the crew of the vessel 

 together with scientific observers David Harrington and Stewart Law and 

 Captain Jim McMurrey. From Florida State University came Reed Armstrong, a 

 graduate student under Dr. Robert Stevenson Accompanying the author from 

 Texas A&M University was chief marine technician Kenneth S. Bottom. 



At the outset, there was no fixed cruise plan. The first objective was 

 to retrace a line containing observations made immediately prior to hurricane 

 HILDA from the r/v ALAMINOS of Texas A&M University. The plan, as completed, 

 is shown in Figure 3* T^^hen the point H-9 was reached the boundary of the cold 

 water area was reached and sea temperature conditions appeared to be at almost 

 prehurricane HILDA values • It was decided to make a section from there 

 perpendicular to the hurricane path. This section v&s made so as to pass the 

 position of the anchored buoy NOMAD from which regular observations were being 

 collected. The next section to the north was chosen across the path at the 

 point of maximum hurricane intensity. In the final run from BT 57 to 63, 

 Figure 3^ a line was repeated along which observations had been made prior to 

 the hurricane by the Bureau of Commercial Fisheries.. Most of the observations 

 collected on the cruise of the GUS III were made at times 5 to 10 days after 

 passage of the storm at the same station locations . 



Although there apparently had been no systematic observations previously 

 under similar circumstances, there are indications in the literature that 

 areas of low sea-surface temperature are often found in the wake of a hurricane, 

 (Fisher, I958, and Jordan and Frank, 196^). Hidaka, 1955^ reported similar 

 cold areas and developed a theory which indicated that there would be con- 

 siderable upwelling in the center of a hurricane and that a cyclonic current 



